Method of and apparatus for welding



c. l.. PFEIFFE'R METHOD OF AND APPARATUS FR WELDING Jan'. 28, 1930.

Filed ooi. ZA, 1927 Patented dan. 28, 1930 UNITED STATES OFFICE Y CONRAD LOUIS PFEIFFER, F CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK :METHOD OF AND tUPP.AJM-LTUS FOR WELDING Application led ctober 3, 1927. Serial No. 223,645.

This invention relates to a method of and apparatus for Welding, and mOreparticularly of material-having a high electrical 'con` ductivity Without fusing the electrodes to the sheets. l

The invention contemplates the provision of a methodand an apparatus for practicing the method in which the current density in the electrode at the juncture of the electrode and sheet is small as compared to the current density in the area of contact between the sheets. In accordance with one embodiment of theinvention, the sheets to be Welded are brought into contact at the point Where the Weld is to be located and the Welding current is applied to a larger area surrounding the point of contact, the sheets to be Welded being sepa-rated except for their central points of Contact by means 0f insulating strips.

' It is believed that` a complete understanding of the invention may be had by reference to the following description taken in con- .junction with the accompanying drawing,

in which Fig. 1 is a side elevation, partly in section, l

of a Welding apparatus With a diagrammatic representation of the Welding circuit, and

Fig. 2 is a plan view taken on line 2 2 of Fig.

Referring to the drawingsin which Athe same reference characters designate similar parts in the several views, an annular elec-4 trode 5 is shown mounted ona base 6. Cooperating'with the'electrode 5 is a second annular or cup-shaped electrode 7 carried by an arm S which is provided With a handle 9 and is pivotally supported on a standard 11 mounted on the base 6. Attached to the base and disposed centrally of the annular elec 'trede 5 is a contact member 12 of insulating material Which in conjunction With a similar contant member 14 mounted in the upper electrode serves toforce the sheets to be welded into iirm engagement at the point When the Weld is to be formed. The contact member 14 is provided with an enlarged portion 15 which fits into a cylindrical cavity 16 in the electrode 7 and is held against a nut 18 threaded into the electrode 7 by means of a spring 19. The resilient mOunting of the contact member 14`causes the member to engage the Work With a definite pressure and at the same time compensates for any variation in the thickness of the sheets to be Welded in allowing the electrodes to engage l the sheets throughout their contact areas.

In practicing the method in connection with thel Welding of composite diaphragms for converting electrical impulses into sound as employed in telephone transmitters, a disk 21 of a highly conductive metal such as copper, or aluminum, is placed concentrically on the lower electrode and a pair of insulating inserts 22-22 are placed upon the disk. Each of the inserts 22 is provided with .a central cut-out portion 23 towards which the insert is tapered along each radius. A; second disk 24 of similar composition is then placed upon the inserts and the upper electrode is brought intol engagement therewith by means of the handle 9. Due to the Jformation of the inserts 22-22 the contact members 12and 14v will force the disks 21 and 24 into contact with each other over a small central area.' When the parts are in the position shown in F ig. 1 a current is applied through a transformer 25 energized from any suitable source of power (not shown). On account of the large contacting areas of the electrodes with the material to be Weldedpath, but as the current from Athe entire pe-Y eliminated, l' and while the inventlon is de- L I' scribedy and illustrated by aspecicembodiscope of the invention. y

ment it will be understoodthat this is'merely av convenient and useful form of the inven' tion which is capable of many'other modifica! tions without departing from the spirit and 'Y What is, claimed is:

1. A method of weldin thin sheets of material, which consists of exingthe sheets so i as to cause them to contact at a small area I applying current to an annular area of'the sheets surrounding the contacting area, land converging the current toward the contacting area to increase its'density and forma weld.

2. VA. method of welding thin sheets of material, which consists of insulating portions of the ysheets from each other, `flexing the sheets to causeuninsulated portions ithereof. to Contact, and applying a welding current I spaced from the area of Contact of the sheets and to a larger area than the contact area.

j 3. In an apparatus for welding sheet materia-ls, rem'ovable means for insulating por tions of the-sheet from each other, means for contacting the sheets at a point `not insulated and'a pair of electrodes covering larger areas than the contact area of the sheets for applying. a welding current to the sheets.4

which consists of interp'osing an apertured insulating member between the sheets, apply` tcting area: t0 6560i? a weld'between'the sheets.

9. In an apparatus for welding sheet ma-V terial, a removable insert for insulating portions of the sheetfromeach other, a pair.

of electrodes for engaging the insulated portions of the sheets to apply a welding current thereto', and a pressure member insulated from one lof theelectrodes and yieldably mounted therein for causing a contact between uninsulated portions of the sheetstoy be welded.

10. In an apparatusfor welding sheetmaterials, a pair of electrodes, an insulatinglinserttapering toward 'a cutout portion, contact members mounted in the electrodes for causing the-'sheets to be welded to contact through i the cutout portion, and'mea-ns for applying a welding current to the electrodes.

In witness whereof, I hereunto subscribe my7name this 23d day of September, A.. D. 192 i" A CONRAD LOUIS PFEIFFER.

4. In an apparatus for welding sheet mai terials, a pair of annular electrodes, and a contact member insulated from and disposed within the contacting area of each of the elec' trodes,said 'contact members being adapted to form a contact between thesheets to be welded.

5. In an apparatus for welding sheet materials, acup-sha edelectrode, a contact member y insulated within the electrode, meansfor engaging the electrode with a sheet of material, and rmeans forl causing, the contact member to contact the sheet with other material to be welded.

6. In an apparatus for welding sheet materials, a cup-shaped electrode, a contact memmounted therein, and means for engaging the contact member with a sheet to engage the L sheet with material to be welded thereto.A

'7. In an apparatus for weldingsheet materials, arpair olf electrodes, a plurality of electrodes for causinfr the sheets to be welded to contact through the aperture, and means for applying a welding current .to the electrodes. Y

8. A methodof welding sheets of material.

rom the electrode disposed ber insulated from the electrode and yieldably -f 

